An assessment workflow to recover microplastics from complex biological matrices

This published study developed a criteria-guided workflow to assess the effectiveness of microplastic separation methods on complex marine biological matrices. More specifically, the use of four microplastic separation methods commonly applied in the literature (nitric acid, HNO3, and potassium hydroxide, KOH, digestions, and sodium chloride, NaCl, and potassium iodide, KI, density flotations) were evaluated on four abundant marine taxa (hard coral, sponge, sea squirt, sea cucumber) using five environmentally relevant microplastics (fragments of polyethylene, polystyrene, polyethylene terephthalate, and polyvinylchloride, as well as rayon fibres). Methods were deemed efficient when (1) rates of sample clarification were appropriate, (2) effects on physical and chemical characteristics of microplastics were negligible, and (3) recovery rates of spiked microplastics into sample matrices were high. Specimens of Acropora millepora (hard coral), Rhopaloeides odorabile (sponge), Polycarpa aurata (sea squirt), and Holothuria atra (sea cucumber) were opportunistically collected from five reefs in the central Great Barrier Reef Marine Park (Rib Reef, Taylor Reef, Feather Reef, John Brewer Reef, Farquharson Reef) in 2017 and 2019. Irregular microplastic fragments and fibres were produced in the laboratory at the Australian Institute of Marine Science (AIMS), in Townsville (Queensland, Australia). This work was primarly conducted through controlled laboratory experiments at AIMS. Microplastic sizes were statistically analysed using general linear model in R. All other parametres assessed were not statistically analysed.